For example, a technique for forming a semiconductor device by forming a thin-film stack structure on one main surface of a substrate composed of a semiconductor (semiconductor substrate) has generally been made use of. It is noted that the main surface herein refers to a largest, major surface of surfaces, and particularly in a case of a substrate, it refers to a surface on which a semiconductor device is to be formed.
In order to improve processing accuracy of a semiconductor device to be formed, preferably, the main surface of the substrate is flat and bent to a lesser extent. If the main surface of the substrate is flat, dimension accuracy and form accuracy of a pattern of the semiconductor device to be formed can be enhanced. For example, Patent Document 1 shown below discloses a single-crystal substrate of silicon carbide in which bending at the main surface is lessened.